US 6,905,642 B2 · Method and continuous production line of plastic tubes with bi-axial drawing, and resulting plastic tube

Abstract

The invention concerns a continuous manufacturing method which consists in producing a blank (E) by extrusion, bringing said blank to a temperature for molecular orientation, passing said blank around a radial expansion mandrel (12); gauging and cooling while subjecting the blank to axial traction. The radial expansion produced on the mandrel (12) is partial so that the internal diameter (B) of the blank (E), when it leaves the mandrel, is less than the nominal internal diameter (D) of the finished tube; performing an additional radial expansion of the blank, up to its nominal diameter, by internal fluid pressure. In permanent operating conditions, the inner surface of the blank (E) is no longer in contact with the mandrel (12).

Claims25

Dependent claims

A process for continuously manufacturing plastic pipes with biaxial drawing, comprising:

forming a tube blank by extrusion, the tube blank being taken to the molecular orientation temperature, made to pass around a radial expansion mandrel member, and sized and cooled while being subjected to an axial pulling force, wherein the radial expansion performed on the mandrel member is partial so that the inside diameter of the tube blank, when it leaves the mandrel member, is smaller than the nominal inside diameter of the finished pipe;
and
performing a further radial expansion of the tube blank, up to its nominal diameter, by an internal fluid pressure;
whereby, in the steady operating state, the internal surface of the tube blank is no longer in contact with the mandrel member.

1 more element

Dependencies are inferred from the claim text.

Method and continuous production line of plastic tubes with bi-axial drawing, and resulting plastic tube

Life of this patent

Method and continuous production line of plastic tubes with bi-axial drawing, and resulting plastic tube

Life of this patent

Abstract

Claims25